Physical and emotional changes during the luteal phase of the menstrual cycle (PMS) are very common among women. The cause of PMS is unknown and may be related to interactions between steroid hormones and the neurotransmitter systems. The ovarian steroid hormones and the monoamine neurotransmitters are known to play a significant role in the diagnostic and treatment of PMS. The main goal of this project is to establish a correlation between the levels of the ovarian steroid hormones and the monamine neurotransmitters in the plasma of PMS patients and compare it to those of non-PMS healthy control subjects. This study may lead to better understanding the etiology of PMS and hopefully lead to improved diagnostic and treatment strategies for this syndrome. The quantitative analysis of steroids and neurotransmitters in plasma will be performed by the gas chromatography mass spectrometric technique (GC/MS). Statistical analysis will be made to measure significant correlation between these components. The blood samples will be obtained from the Williams Medical Clinic, Holly Springs, MS. Two undergraduate students from Rust College will have the opportunity to participate in this research project through hands-on experience.